Jasper was born at the Bishop of Ely's manor at Hatfield, Hertfordshire in 1431, his parents' second child. His older brother, Edmund, was born at Much Hadham Palace in 1430. His younger brother, Owen, was born in 1432 at Westminster Abbey, when the Dowager Queen was visiting her eldest son and her water broke prematurely, forcing her to seek the help of the Abbey's monks. According to Henry VII's personal historian Polydore Vergil, Owen was taken and raised by the monks to become a member of the order, living under the name Edward Bridgewater until his death in 1502. Vergil also mentions a daughter who became a nun, but little is known of her. Catherine's last child would be born in 1437, mere days before her own untimely death on 3 January.[3]

After Catherine's death, Owen Tudor was arrested and sent to Newgate prison. Jasper, Edmund, and possibly their sister were put into the care of Katherine de la Pole, a nun at Barking Abbey, in Essex, from July 1437 to March 1442.[4] She was the sister of William de la Pole, 1st Duke of Suffolk, a great favorite of Henry VI, and was able to provide Jasper and his siblings with food, clothing, and lodging. They were also permitted servants to wait upon them as the King's half-siblings.[5]

In 1442, their half-brother the King began to take an interest in their upbringing.[6] Sometime after March 1442, Jasper and his brother were brought to live at court. Henry arranged for the best priest to educate them intellectually and morally. The brothers also received military training; when they grew up they were given military positions.[7] Jasper was recognised as Henry VI's uterine brother when he was created Earl of Pembroke.[8]

Owen Tudor was released from prison, most likely thanks to his stepson Henry VI, who after providing for his stepfather, also provided for his two half-brothers. It is not clear whether Henry VI had known of the existence of his half-brothers until his mother told him while she was dying in Bermondsey Abbey. It was after her death that Henry would begin to care for them and eventually raise them to the peerage by giving both brothers earldoms. Jasper became Earl of Pembroke on 23 November 1452, the seventh creation.[9] In turn, Edmund and Jasper swore unwavering loyalty to Henry and fought and promoted him and his Lancastrian family's interests persistently throughout their lives.

Owen and Catherine's marriage was not recognised by the authorities, in large part due to the secrecy under which it was accomplished, and so the legitimacy of Jasper and his two (or three) siblings was questionable. However, Jasper enjoyed all the privileges appropriate to his birth, including being invested as a Knight of the Garter. After 1485, he would describe himself as the “high and mighty Prince Jasper, brother and uncle of Kings, Duke of Bedford and Earl of Pembroke”.[10] During his time at court, Jasper constantly tried to work with the Duke of York and other nobles in order to try to stop the infighting between the two houses.[11] It was after the death of his elder brother, Edmund, that Jasper took over the responsibility of maintaining the Lancastrian ties within Wales. Along with this, he took into his care his sister-in-law and infant nephew.[12]

On the accession of the Yorkist King Edward IV in 1461, he was subject to an attainder for supporting his Lancastrian half-brother, the deposed King Henry, to whom Jasper was loyal. He strove to place his half-nephew Prince Edward of Lancaster on the throne and provided absolute loyalty to his royal half-brother and Margaret of Anjou, his half-brother's wife. Jasper would also help his other sister-in-law Lady Margaret Beaufort assist her son Henry Tudor to win the throne in 1485 as King Henry VII, father of King Henry VIII.

Jasper Tudor also brought up his nephew, Henry Tudor, whose father had died before his birth. After being welcomed by King Louis XI of France in 1462, Jasper stayed in France for 6 years before returning to North Wales in 1468. On his return, Jasper lost Pembroke Castle to William Herbert, when Herbert was given the title of Earl of Pembroke by King Edward IV.

Jasper Tudor briefly regained the earldom of Pembroke a couple of years later when his half-brother, King Henry VI, was restored to the throne, but following the return of King Edward IV from temporary exile in 1471, Jasper fled again to the continent. During his time on the continent, he travelled and attempted to gather support for the Lancastrian cause.[15] While escaping from Tenby with his nephew Henry, storms in the English Channel forced them to land at Le Conquet in Brittany, where they sought refuge with Francis II, Duke of Brittany. Duke Francis II housed Jasper, his nephew, and the core of their group of exiled Lancastrians at the Château de Suscinio in Sarzeau. And although King Edward IV placed diplomatic pressure on the Duke of Brittany, the uncle and nephew remained safe from the clutches of the Yorkist king, who died later in April 1483. For 11 years, the Château de Suscinio became an armed camp, alert against any attempt to kidnap Jasper and Henry and return them to England, where they were under attainder and would have been promptly executed as threats to the Yorkist rule.

In October 1483, the Tudors launched an invasion of England from Brittany. However, the invasion failed and Jasper Tudor and his nephew Henry returned to Brittany. In mid-1484, when the Duke of Brittany was incapacitated with illness, his treasurer, Pierre Landais, who took over the reins of government, reached an agreement with the new Yorkist king, Richard III of England, to send Jasper and his nephew back to England in exchange for a pledge of 3,000 English archers to defend Brittany against a threatened French attack. John Morton, a bishop of Flanders, learned of the scheme and warned the Tudors in time. Jasper and Henry then managed to escape separately, hours ahead of Landais' soldiers, across the nearby border into France.[16] They were received at the court of King Charles VIII of France who allowed them to stay and provided them with resources.[17] Shortly afterwards, when Duke Francis II had recovered, he offered the 400 remaining Lancastrians, still at and around the Château de Suscinio, safe-conduct into France and even paid for their expenses.

On Henry Tudor's subsequent accession to the throne as King Henry VII of England in 1485, Jasper Tudor had all previous attainders annulled,[18] and was thus restored to all his former titles, including Knight of the Garter, and was created Duke of Bedford. In 1488, he took possession of Cardiff Castle.

Jasper Tudor acknowledged paternity of no illegitimate children during his lifetime and none are mentioned in his will.

The earliest source for any illegitimate child of Jasper Tudor appears to be the Heraldic Visitation of the northern counties in 1530 by Thomas Tonge, Norroy King of Arms (d. 1534).[20] The records of Tonge's Heraldic Visitation were first published in 1836, by the Surtees Society.[21] They contain a claim by Prior Gardener, of Tynmouth Monastery in Northumberland, to be the son of Ellen, a bastard daughter of Jasper Tudor, Duke of Bedford, and her husband William Gardener. The heraldic arms claimed by Prior Gardener include a shield impaling the arms of Jasper Tudor, 'debruised by a bend sinister'.[22]

The next source dates from the late 17th Century - nearly two hundred years after Jasper Tudor's death. William Dugdale's Baronage of England (1675-6) states that Jasper Tudor "departed this Life ... leaving no other Issue than one Illegitimate Daughter, called Ellen, who became the Wife of William Gardner, Citizen of London".[23] Dugdale (1605-1686), an eminent antiquarian and scholar,[24] was Norroy King of Arms (1660-1679) and Garter King of Arms (1679-1686). The records of Tonge's 1530 Visitation held by the College of Arms would have been available to Dugdale.[25]

In the 19th Century the account was embroidered, to make Ellen (or Helen) the mother of Stephen Gardiner, Bishop of Winchester and Lord Chancellor.[26] The account that Stephen Gardiner, Bishop of Winchester, was a descendant of Jasper Tudor is now discredited : it appears that this assertion arose from confusing Stephen Gardiner, the Bishop, with Thomas Gardiner, Prior of Tynmouth.[27]

Subsequent accounts added the identity of the mother of the supposed illegitimate daughter, Ellen or Helen - as Myfanwy verch Dafydd (1436-1485). Also added was a second illegitimate daughter by Myfanwy verch Dafydd : Joan, (b. Snowdon, Wales c. 1453, d. 1469), wife of William ap Yevan, and mother of twins Sir John Williams and Morgan Williams (born Llanishen, Glamorganshire, Wales, 1469). It was further claimed that Jasper Tudor, through Joan and her son Morgan, was an ancestor of Oliver Cromwell. No reliable sources appear to support these assertions.

^The 1530 Heraldic Visitations were carried out by the Kings of Arms under warrants granted by King Henry VIII.

^Edited by the antiquarian W. Hylton Dyer Longstaffe FSA. At the time of publication in 1836, there were two copies of the records of this Visitation : one, presumed to be Tonge's original notes, was held in the College of Arms; the other, a more polished copy, was included with the Harleian MSS in the British Museum. The 1836 publication publishes the copy in the Harleian MSS without collation to the College of Arms copy : see the preface to the 1836 publication.

^Heraldic Visitation of the Northern Counties in 1530 by Thomas Tonge, Norroy King of Arms (1836); online at [1]; section on 'The Monasterie of Tynmouth' (pp 35-6 in the 1836 publication). This states that the Prior "whose name ys GARDENER ... ys descended of the noble Queen Kateryn, wyfe of Kyng Henry the vith ... For the said Quene Kateryne was after maryed to Owayn Teddur, by whom he had yssue ... Jasper Duc of Bedford. Whiche Jasper begat a bastard doughter called Ellen, maryed Willyam Gardener, who was father to my said Lord Priour". The record adds : "Be it noted that the said PRIOUR OF TYNMOUTH, hath given unto me, Norrey King of Arms of the North parties, this pedigre and armes of his awne reporte, which he woll offerme at all tymes to verefy and approve before the Kynge and his Counsaill, that this pedigre is true and the armes also."

^"Iasper of Hatfeild Earl of Pembroke and Duke of Bedford", in William Dugdale's Baronage of England (1675-6) vol iii p. 241 at 242, online at [2] retrieved 15 February 2018.

^See College of Arms, 'Records and Collections' (retrieved 15 February 2018); and the preface to the 1836 Surtees Society publication of Tonge's 1530 Visitation. As Norroy King of Arms, Dugdale, like Tonge, was the member of the College of Arms with heraldic jurisdiction for the counties of England north of the River Trent.

^See, for example: Burke, Genealogical and Heraldic Dictionary of the Peerages of England, Ireland and Scotland (1831) at pp 524-5; W. A. J. Archbold's entry on "Jasper Tudor" in the Dictionary of National Biography, 1885-1900, Vol. 57: "[Jasper Tudor] ... left an illegitimate daughter, Helen, who is said to have married William Gardiner, and to have been the mother of Stephen Gardiner [q.v.]"; G.E.Cokayne's The Complete Peerage, First edition (1887-1898), 2nd revised edition ed by V. Gibbs, vol ii (1912) at p. 73 n. (d): "Helen, his illegit. da. m. William Gardiner, citizen of London, and was mother of Stephen, the celebrated Bishop of Winchester".